KR100626751B1 - Hierarchically Ordered Photo-Functional Semiconductor Doped Nanoporous Membrane and Method for Preparing the Same - Google Patents

Abstract

The present invention relates to a dual nanoporous alignment layer into which a photofunctional semiconductor is introduced and a method of manufacturing the same, wherein the photofunctional semiconductor nanoparticles are introduced into a nanoporous alumina macroporous membrane having a size of 180 to 220 nm. The present invention relates to a dual nanoporous alignment layer into which a photofunctional semiconductor having a silica fine nanoporous material having a size of nm is introduced, and a method of manufacturing the same.

Nanoporous, Alignment Film, Photofunctional Semiconductor, Cadmium Sulfide

Description

Hierarchically Ordered Photo-Functional Semiconductor Doped Nanoporous Membrane and Method for Preparing the Same

1 is a scanning electron micrograph and a transmission electron micrograph of a macroporous alumina support filled with silica fine nanoporous material introduced with 1 mol% cadmium sulfide according to Example 1 of the present invention.

2 is a scanning electron micrograph and a transmission electron micrograph of a dual nanoporous alignment layer introduced by increasing the ratio of cadmium sulfide to 3 mol% according to Example 2 of the present invention.

3 is a transmission electron micrograph of a dual nanoporous alignment layer introduced by increasing the ratio of cadmium sulfide to 5 mol% and 10 mol% according to Examples 3 and 4 of the present invention.

FIG. 4 is a graph and photograph showing incineration X-ray diffraction results of porous alumina alignment layers filled with fine nanoporous silica nanofibers in which cadmium sulfide is introduced according to Examples 1 and 2. FIG.

FIG. 5 is a graph showing nitrogen adsorption-desorption isotherm of the dual nanoporous alignment layer according to the difference in the amount of cadmium sulfide introduced.

6 is a graph showing the absorption and fluorescence spectra of the dual nanoporous alignment layer according to the difference in the amount of cadmium sulfide introduced according to Examples 1 and 2.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual nanoporous alignment layer into which a photofunctional semiconductor is introduced and a method of manufacturing the same. The present invention relates to a dual nanoporous alignment layer into which a photofunctional semiconductor is prepared by injecting silica fine nanoporous (about 6 nm) material into which nanoparticles are introduced, and a method of manufacturing the same.

Nanometers (㎚: 10 ^-9 m) nano-porous material having an aperture size of is receiving great interest in many fields, such as the synthesis of the separate, new nanocomposite of heterogeneous catalyst or nano-sized molecules because of their unique properties nano . To date, metal oxides and semiconductor materials of various compositions have been made of nanoporous materials with aperture sizes of several nanometers, but these materials are usually micrometer (μm: 10 ^-6 m) particles. In most cases it was prepared in the form of a powder consisting of. Therefore, manufacturing nanoporous materials having excellent alignment in a wide area of about square centimeters (cm 2) has been considered a very difficult technology in related fields. Despite these technical difficulties, the membrane-type nanoporous material having a diameter of several nanometers is expected to be widely applicable in various scientific and technical aspects due to the alignment characteristics of nanopores arranged in a certain direction. Research into the production of nanoporous materials has been actively attempted around the world.

Recently, A. Yamaguchi, et al., Used a self-organized template of monomolecular surfactants within the macropores of nanoporous alumina to achieve a 3 nm aperture. Nanoporous materials with dual nanoporous structures with size have been developed. The prepared nanoporous alignment layer has a size selective molecular sieve effect in the range of several nanometers (A. Yamaguchi, et al., Nature Mater. , 2004, 3 , 337). The oriented membrane with both of these faces is expected to have great potential in related applications (molecular catalyst reaction, sensor, etc.) if proper functionality is introduced into the pores.

Accordingly, in the present invention, visible light is injected by injecting a silica fine nanoporous (about 6nm) material into which a photofunctional semiconductor (cadmium sulfide) nanoparticle is introduced into the nanoporous alumina macroporous (about 200nm) membrane. It is a new development of a dual nanoporous alignment layer containing the unique photofunctionality of semiconductor nanoparticles in the region.

It is an object of the present invention to provide a dual nanoporous alignment layer into which a photofunctional semiconductor is introduced.

Another object of the present invention is to provide a method for producing a dual nanoporous alignment layer into which a photofunctional semiconductor is introduced.

The above and other objects of the present invention can be achieved by the present invention described below.

In one embodiment, the present invention provides a nanoporous alumina macroporous membrane having a size of 180 to 220 nm, preferably 200 nm, wherein 5-10 nm, preferably 6 nm of photofunctional semiconductor nanoparticles are introduced. Provided is a dual nanoporous alignment layer into which a photofunctional semiconductor is introduced, having a silica fine nanoporous material having a size.

The photofunctional semiconductor may be selected from the group consisting of CdS, ZnS, PbS and TiO ₂ , preferably CdS.

In the present invention, the "macropores" of the nanoporous alumina generally mean that the size of the nanopores is 50 nm or more, and the term "fine nanopores" means that the size of the nanopores is 50 nm or less.

In still another aspect, the present invention provides a method for producing a dual nanoporous alignment layer into which a photofunctional semiconductor is introduced, comprising the following steps:

I) immersing the nanoporous alumina thin film in a octadecyltrichlorosilane solution dissolved in benzene, and refluxing for 8 to 12 hours to modify the inner surface of the pores of the nanoporous membrane with an organic material;

II) preparing a lyotropic precursor solution to introduce photofunctional semiconductor properties into the dual nanoporous alignment layer;

III) After dipping the nanoporous alumina support into the lyotropic solution and slowly stirring for 10 to 14 hours to completely fill the pores, the membrane was kept for 10 to 14 hours while the temperature was maintained at 50 to 90 ° C. Inducing a gelation reaction;

IV) exposing the nanoporous alumina support membrane filled with lyotropic supramolecular precursors to excess hydrogen sulfide gas (10 ml) for 8-12 hours; And

V) After removing some of the bulk product remaining on the surface of the membrane after the reaction, to remove the triblock copolymer template molecule used as a self-assembled template in the preparation of a nanoporous alignment layer having a dual structure Calcining at 300 to 400 ° C. for 1 to 3 hours to produce a dual nanoporous alignment layer.

The lyotropic solution is a silica precursor; Precursors selected from the group consisting of titanium oxide, cadmium, zinc and lead, preferably cadmium; And a triblock copolymer may be prepared by dissolving in an ethanol solution to which an acid is added. The acid added to the ethanol solution may be selected from the group consisting of nitric acid, sulfuric acid, and hydrochloric acid, preferably nitric acid.

The molar ratio of silica to cadmium sulfide in the lyotropic solution may be 1: 0.01 (1 mol%) to 0.10 (10 mol%), preferably 1: 0.03 (3 mol%).

In the present invention, "lyotropic" refers to a liquid crystal system in which the supramolecule structure varies in various ways depending on the concentration of the surfactant molecule in the solution.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are merely to aid the understanding of the present invention, and the scope of the present invention is not limited to the following examples.

Example 1

A nanoporous alumina thin film (Whatman, Anodisc) having a micro aperture of 200 ± 20 nm, a width of about 5 cm 2, and a thickness of 60 μm was used as a support to prepare a double nanoporous alignment layer having micro pores in the macro pores. Used. Octadecyltrichlorosilane dissolved in benzene (Sigma-Aldrich Chemical Co .; Catalog No. 104817-25G, 90 +%, St. Louis, USA to facilitate insertion of lyotropic precursor solutions) ) The nanoporous alumina thin film was immersed in the solution, and then refluxed for 10 hours to modify the inner surface of the pores of the nanoporous membrane with an organic material. In order to introduce photofunctional semiconductor properties into the dual nanoporous alignment layer, a lyotropic precursor solution is used as a supramolecular body of silica precursor, cadmium precursor, and fine nanoporous material (BASF Chemical Co., New Jersey, USA) Triblock copolymer is prepared by dissolving uniformly in ethanol solution to which nitric acid is added. Detailed experimental procedures for preparing a lyotropic precursor solution are as follows. 1 g of Pluronic F127 and 2.1 g of tetraethylorthosilicate (TEOS, Aldrich Chemical Co .; Catalog No. 13190-3, 98%, Milwaukee, USA), 0.03 g of cadmium nitrate tetra Hydrate (cadmium nitrate tetrahydrate) (Kanto Chemical Co .; Catalog No. 07022-00, 98%, Tokyo, Japan), and 0.34 nitric acid (Matsunden Chemical Co., 60%, Osaka, Japan) 0.54 g of 2.3 g Ethanol (Merck KGaA; Catalog No. 111727, 99.9>%, Darmstadt, Germany) was added to the solvent and stirred. The lyotropic solution was tested by adjusting the mole ratio of silica to cadmium sulfide to 1: 0.01 (1 mol%). The nanoporous alumina support was immersed in the lyotropic solution above and then stirred slowly for 12 hours to completely fill the pores. Thereafter, the membrane was kept at 60 ° C. for 12 hours to induce a gelation reaction. The nanoporous alumina support membrane filled with lyotropic supramolecular precursors was exposed to excess hydrogen sulfide gas (10 ml) for 10 hours and immediately showed the inherent yellow color of cadmium sulfide. After removing some of the bulk product remaining on the surface of the membrane after the reaction, to remove the triblock copolymer template molecule used as a self-assembled template in the preparation of a nanoporous alignment film having a dual structure Calcined at 350 ° C.

Example 2

The same procedure as in Example 1 was conducted except that the molar ratio of silica to cadmium sulfide in the lyotropic solution was adjusted to 1: 0.03 (3 mol%).

Example 3

The same procedure as in Example 1 was conducted except that the molar ratio of silica to cadmium sulfide in the lyotropic solution was adjusted to 1: 0.05 (5 mol%).

Example 4

The same procedure as in Example 1 was performed except that the molar ratio of silica to cadmium sulfide in the lyotropic solution was adjusted to 1: 0.10 (10 mol%).

[Test Example]

The shape, structural and optical properties of the dual nanoporous alignment layer into which the optical functional semiconductors prepared in Examples 1 to 4 were introduced were measured by scanning electron microscope (FE-SEM; JEOL, JSM-6700F), transmission electron microscope (TEM; JEOL, 2010), using a nitrogen adsorption and desorption meter (Micromeritics, ASAP 2010), a diffuse reflection spectrometer equipped with an integrating sphere (Jasco, ISV-469) (Jasco, V-550), and a fluorescence spectrometer (Hitachi, F-4500). Measured. Incineration X-ray diffraction was performed using synchrotron radiation in the 3C2 X-ray ray (λ = 0.1542 nm) line of the Accelerator Laboratory of Pohang University of Science and Technology, where the X-rays were transmitted through the double nanoporous alignment layer. Scattering experiments were performed by irradiating the light vertically.

[Test Example 1]

1 is a scanning electron micrograph of a macroporous alumina support filled with silica fine nanoporous material introduced with 1 mol% cadmium sulfide according to Example 1. FIG. In Figure 1 (A) shows the top surface of the macroporous alumina support, (B) shows the side of the macroporous alumina support, (C) after removing the nanoporous alumina support with 1M sodium hydroxide solution The transmission electron micrograph of the obtained fine nanoporous silica nanofiber into which the cadmium sulfide was introduce | transduced is shown.

As shown in FIGS. 1A and 1B, the silica nanostructures into which cadmium sulfide was introduced showed a fibrous form, and these composite nanofibers were filled in the pores of a large-area nanoporous alumina support. .

In FIG. 1C, after dissolving the large nanoporous alumina support with 1M sodium hydroxide solution, it was observed from the transmission electron microscopic analysis that the individual composite nanofibers had a mesh-like nanopore morphology having a diameter of about 6 nm. Structurally, very interestingly, unique nanostructures in the form of onion peels were observed from the cut surfaces of the composite nanofibers (arrows).

FIG. 2 is a scanning electron micrograph and a transmission electron micrograph of a dual nanoporous alignment layer introduced by increasing the ratio of cadmium sulfide to 3 mol% according to Example 2. FIG. Similar to the 1 mol% condition in Example 1 showed a nanofiber structure well filled inside the large nanoporous alumina support, it was confirmed that the unique fine nanopore structure is also well maintained.

3 is a transmission electron micrograph of a dual nanoporous alignment layer introduced by increasing the ratio of cadmium sulfide to 5 mol% and 10 mol% according to Examples 3 and 4. FIG. As shown in FIG. 3A, the silica nanofibers having 5 mol% of cadmium sulfide maintained relatively well the fine nanopore structure having a 6 nm diameter. As shown in FIG. 3B, the silica nanofibers having 10 mol% of cadmium sulfide were introduced. It can be seen that the fine nanopore structure has a unique structural characteristic that is somewhat disordered.

[Test Example 2]

FIG. 4 shows small-angle X-ray diffraction results of porous alumina alignment layers filled with fine nanoporous silica nanofibers in which cadmium sulfide is introduced according to Examples 1 and 2. FIG.

The macroporous alumina alignment films filled with the fine nanoporous silica incorporating cadmium sulfide prepared according to Examples 1 and 2 exhibit various X-ray diffraction patterns in the incineration region. From the results of the diffraction analysis, both bipolar nanoporous alignment layers in which cadmium sulfide was introduced in different amounts (1 mol% and 3 mol%) of Examples 1 and 2 had lamellar structure ( d ₁₀₀ = 10.64 nm) characteristics. Confirmed.

As shown in FIG. 4B, since the X-rays were irradiated vertically in the horizontal direction of the membrane, these results showed a unique onion shell-like concentric shape of the nanoporous nanofibers filled inside the large nanoporous alumina support. It is thought that it originates in the pseudo-lamellar structure which this has.

[Test Example 3]

Figure 5 shows the nitrogen adsorption-desorption isotherm of the dual nanoporous alignment layer according to the difference in the amount of cadmium sulfide introduced: 1 mol% (square), 3 mol% (circle), fine nanoporous silica Large nanoporous alumina support (triangle) without the introduction of the complex. The graph inserted in FIG. 5 shows the main aperture size predicted by the BJH calculation.

In FIG. 5, a typical capillary condensation phenomenon observed in the nanoporous material was observed. From the measurements, the Brunauer-Emmett-Teller (BET) surface area and pore volume were 25.1 m ² g ^-1 and 0.046 cm ³ g ^-1 for dual nanoporous alignment films with 1 mol% cadmium sulfide according to Example 1, respectively. In the case of the dual nanoporous alignment layer in which 3 mol% cadmium sulfide was introduced according to Example 2, the measurement was 38.6 m ² g ⁻¹ and 0.050 cm ³ g ⁻¹ , respectively. The interpolated graph of FIG. 5 shows that the main aperture size measured by Barrett-Joyner-Halenda (BJH) calculation was approximately 6 nm for both dual nanoporous alignment layers, which was observed from transmission electron micrographs. It matches well with the size of nanofibers. These structures and nitrogen gas adsorption-desorption characteristics support the fact that external gas molecules can pass well into the double nanoporous alignment layer into which the semiconductor fabricated in this study is introduced.

[Test Example 4]

Figure 6 shows the absorption spectrum of the dual nanoporous alignment layer according to the difference in the amount of cadmium sulfide introduced (1 mol%, 3 mol%, 5 mol%, and 10 mol%) prepared according to Examples 1 to 4. The dotted line in the graph of FIG. 6 shows the absorption spectrum for the large nanoporous alumina support to which the fine nanoporous silica composite was not introduced.

The absorption spectrum of FIG. 6 was obtained by applying the Kubelka-Munk function to the diffuse reflection spectrum. The graph inserted in FIG. 6 is a fluorescence spectrum of a dual nanoporous alignment layer in which 3 mol% of cadmium sulfide was introduced. Excitation light of 430 nm was used to obtain a fluorescence spectrum.

As shown in FIG. 6, the large nanoporous alumina thin film used as a support from the absorption spectrum in the visible region for the double nanoporous alignment layer into which the semiconductor is introduced shows no characteristic optical properties, whereas cadmium sulfide is introduced. The dual nanoporous alignment layer thus exhibits a typical absorption transition of cadmium sulfide.

It should be noted that the dual nanoporous alignment layer in which 1 mol% cadmium sulfide is introduced has a absorption spectrum around 460 nm, whereas the alignment film having 3 mol%, 5 mol%, and 10 mol% increases the introduction rate of cadmium sulfide at 480 nm, That is, the start wavelength of the absorption spectrum shifts in the long wavelength to around 503 nm and 515 nm. All of these absorption spectra are shifted to shorter wavelengths than 520 nm, which is the band gap transition of cadmium sulfide in bulk, which is thought to be due to the quantum size effect of cadmium sulfide nanoparticles introduced into the inner wall of the silica fine nanoporous material. .

In addition, the dual nanoporous alignment layer imparted with the optical function by the introduction of cadmium sulfide shows a wide fluorescence phenomenon around the wavelength of 670 nm. Fluorescence over a wide range of stokes is known as fluorescence due to exciton recombination at surface energy levels resulting from surface defects of cadmium sulfide nanoparticles.

The dual nanoporous alignment layer incorporating the optical functional semiconductor according to the present invention is a nanocomposite material having multiple functionalities, and thus can be applied to heterogeneous catalytic reaction systems having high industrial utility and nanosensors showing selective functionality in molecular size. .                     

While the invention has been described in detail above with reference to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope and spirit of the invention, and such modifications and variations fall within the scope of the appended claims. It is also natural.

Claims (6)

An optical functional semiconductor having a silica fine nanoporous material having a size of 5 to 10 nm in which a photofunctional semiconductor nanoparticle is introduced into a nanoporous alumina macroporous film having a size of 180 to 220 nm is introduced. Dual nanoporous alignment layer. 10. The dual nanoporous alignment layer of claim 1, wherein the optical functional semiconductor is selected from the group consisting of CdS, ZnS, PbS, and TiO ₂ . Immersing the nanoporous alumina thin film in a octadecyltrichlorosilane solution dissolved in benzene, and refluxing for 8 to 12 hours to modify the inner surface of the pores of the nanoporous membrane with an organic material; Preparing a lyotropic precursor solution to introduce photofunctional semiconductor properties into the dual nanoporous alignment layer; After immersing the nanoporous alumina support in the lyotropic solution and slowly stirring for 10 to 14 hours to completely fill the pores, the membrane was held for 10 to 14 hours with 50 to 90 ° C. Inducing a gelation reaction; Exposing the nanoporous alumina support membrane filled with lyotropic supramolecular precursors to excess hydrogen sulfide gas (10 ml) for 8-12 hours; And After removing some of the bulk product remaining on the surface of the membrane after the reaction, in order to remove the triblock copolymer template molecule used as a self-assembly template in the production of a nanoporous alignment membrane having a dual structure Calcining at 300 to 400 ° C. for 3 hours to prepare a dual nanoporous alignment layer; A method for producing a dual nanoporous alignment layer into which a photo-functional semiconductor is introduced. The lyotropic solution of claim 3, wherein the lyotropic solution comprises: a silica precursor; Precursors selected from the group consisting of titanium oxide, cadmium, zinc and lead; And a triblock copolymer prepared by dissolving a triblock copolymer in an ethanol solution to which an acid is added. 5. The method of claim 4, wherein the acid added to the ethanol solution is selected from the group consisting of nitric acid, sulfuric acid, and hydrochloric acid. 6. 5. The dual nanoporous alignment layer of claim 4, wherein the molar ratio of silica to cadmium sulfide in the lyotropic solution is from about 0.01 (1 mol%) to 0.10 (10 mol%). Manufacturing method.

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